The present invention relates to improvements in a wire electric discharge machine to conduct machining on a workpiece by electric discharge energy when electric power for machining is supplied between a wire electrode and the workpiece.
FIG. 5 is an arrangement view showing a conventional wire electric discharge machine. In the drawing, reference numeral 1 is a wire electrode, reference numeral 1a is a used wire electrode, reference numeral 2 is a supply bobbin, reference numeral 3 is a tension brake, reference numeral 4 is a column, reference numeral 5 is an upper guide, reference numeral 6 is a workpiece, reference numeral 7 is a lower guide, reference numeral 8 is a lower roller, reference numeral 9 is a lower arm, reference numeral 10 is a saddle, reference numeral 11 is a wire recovery section fixed to the saddle 10, reference numeral 12 is a capstan roller, reference numeral 13 is a pinch roller, reference numeral 14 is a feed motor for driving the capstan roller 12, reference numeral 15 is a hollow wire guide, reference numeral 16 is a wire cutter, reference numeral 16a is a cutting blade of the wire cutter 16, reference numeral 17 is a wire recovery box, reference mark A is a traveling direction of the wire electrode 1, the traveling direction of which is changed by the lower roller 8, reference mark B is a straight line connecting the rotational center of the capstan roller 12 with that of the pinch roller 13, and reference mark C is a point at which the pinch roller 13 is pressed against the capstan roller 12.
The pinch roller 13 comes into pressure contact with the capstan roller 12 at point C when a restoring force generated by a spring not shown acts on the pinch roller 13. The wire guide 15 is used to guide the wire electrode 1, which has passed through a wire electrode holding section provided between the capstan roller 12 and the pinch roller 13, to the wire cutter 16 (after starting wire electric discharge machining, a used wire electrode 1a is guided to the wire cutter).
Next, operation will be explained below. Tension of the wire electrode 1 is controlled by the tension brake 3 arranged on the upstream side of traveling of the wire electrode with respect to the workpiece 6. The wire electrode 1 is held by the capstan roller 12 and the pinch roller 13 which are arranged on the downstream side of traveling of the wire electrode with respect to the workpiece 6 (after starting wire electric discharge machining, a used wire electrode 1a is held by the capstan roller and the pinch roller). While the wire electrode 1 is being held between the capstan roller 12 and the pinch roller 13, the wire electrode 1 is made to travel being pulled by the driving torque generated by the feed motor 14. As described above, while the wire electrode 1 is traveling, electric power for machining is supplied between the workpiece 6 and the wire electrode 1, and wire electric discharge machining is conducted on the workpiece 6.
The used wire electrode 1a, which has been consumed in the process of wire electric discharge machining, passes through the lower guide 7, lower roller 8, lower arm 9, saddle 10 and wire recovery section 11 and is cut by the wire cutter 16 and then accommodated in the wire recovery box 17. Alternatively, in some cases, the used wire electrode 1a is dropped into the wire recovery box 17 and recovered as it is without being cut by the wire cutter 16.
Recently, due to the increases in the sizes of the supply bobbin 2 and the wire recovery box 17, the wire electrode having larger diameter can be used. In this case, the used wire electrode 1a is cut with the wire cutter 16, for example, the used wire electrode 1a is cut with the wire cutter disclosed in Japanese Unexamined Patent Publication No. 9-267221 and recovered.
As shown in FIG. 5, in the case where the capstan roller 12 and the pinch roller 13 are arranged symmetrically to each other with respect to the used wire electrode 1a, that is, in the case where straight line B connecting the rotational center of the capstan roller 12 with that of the pinch roller 13 is perpendicular to wire electrode traveling direction A which has been changed by the lower roller 8 after the completion of the electric discharge, the wire electrode supply is suitably automatized when the wire electrode is connected. However, the following problems may be encountered. Since the used wire electrode 1a, which has been consumed after the completion of electric discharge machining, is held and pulled only by pressing point C at which the pinch roller 13 is pressed against the capstan roller 12, a heavy load is given to the holding section to hold the used wire electrode 1a by the pinch roller 12 and the capstan roller 12 because tension given to the wire electrode 1 changes in the process of electric discharge machining of the workpiece 6. Accordingly, the wire electrode 1a tends to break.
FIG. 6 is a schematic illustration to explain an arrangement of the capstan roller 12 and the pinch roller 13 by which the problem of breaking of a wire electrode can be solved. In the drawing, reference mark D indicates a direction changing point at which the wire electrode traveling direction is changed from wire electrode traveling direction A. Like reference characters are used to indicate like parts in FIGS. 5 and 6.
The arrangement shown in FIG. 6(a) is disclosed, for example, in Japanese Unexamined Patent Publication No. 59-232730, and the arrangement shown in FIG. 6(b) is disclosed, for example, in Japanese Unexamined Patent Publication No. 1-92029. The arrangement shown in FIG. 6(c) is a well known arrangement commonly applied to an actual product. In any arrangement, straight line B connecting the rotational center of the capstan roller 12 with that of the pinch roller 13 is not perpendicular to traveling direction A of the wire electrode 1, the direction of which is changed by the lower roller 8. In the above arrangement, the wire electrode 1 is pulled by an outer diameter portion (portion of the capstan roller 12 round which the wire electrode 1 is wound) of the capstan roller 12 between pressing point C, at which the pinch roller 13 is pressed against the capstan roller 12, and direction changing position D at which the wire electrode traveling direction is changed from wire electrode traveling direction A. Therefore, it is difficult for the wire electrode 1 to break in this arrangement compared with the arrangement shown in FIG. 5 in which the wire electrode is pulled only by pressing point C at which the pinch roller 13 is pressed against the capstan roller 12.
However, the arrangements shown in FIGS. 6(a) and 6(b) have the following problems. When the wire electrodes 1 are connected with each other, it is difficult for the wire electrode 1, the direction of which is changed by the lower roller 8, to be automatically fed between the capstan roller 12 and the pinch roller 13. Accordingly, it is difficult to automatize the feed of the wire electrode 1. The arrangement shown in FIG. 6(c) is suitable for automatization of the feed of the wire electrode 1 in the case of connecting the wire electrode 1 with each other, however, in the arrangement shown in FIG. 6(c), the traveling direction of the wire electrode 1 is changed obliquely downward from wire electrode traveling direction A. Therefore, in the case of connecting the wire electrodes 1 with each other, since the wire electrode 1 is conveyed to the wire recovery section 11 in a machining solution, the machining solution enters the wire cutter 16 from a gap between the capstan roller 12 and the pinch roller 13, which causes a problem in which rust is generated on the cutting blade 16a. 
FIG. 7 is a view showing an example in which the wire cutter 16 is not used in the arrangement shown in FIG. 6(c) and the used wire electrode 1a is dropped as it is into the wire recovery box 17 and recovered. The used wire electrode 1a, which has been consumed in the process of wire electric discharge machining, tends to curl when the traveling direction of the used wire electrode 1a is changed. Since the traveling direction of the used wire electrode 1a is changed by 90xc2x0 by the lower roller 8 and then changed in the reverse direction by the capstan roller 12 and the pinch roller 13, the used wire electrode 1a is curled as shown in FIG. 7. Accordingly, the used wire electrode 1a, which has been recovered into the wire recovery box 17, becomes bulky. As a result, it is necessary to use a larger wire recovery box 17.
The present invention has been accomplished to solve the above problems. It is an object of the present invention to provide a wire electric discharge machine characterized in that: the occurrence of breaking of a wire electrode can be suppressed; the wire electric discharge machine is suitable for automatizing the feed of a wire electrode; a machining solution can be prevented from entering a wire cutter in the case of using the wire cutter; and a used wire electrode can be effectively accommodated in a used electrode wire recovery box in the case not using the wire cutter.
The present invention provides a wire electric discharge machine in which electric power for machining is supplied so that the workpiece is machined by electric discharge energy, and a wire cutter for cutting the used wire electrode is provided, the wire electric discharge machine characterized in that: the capstan roller and the pinch roller are arranged so that direction changing angle xcex8 of the wire electrode, by which the traveling direction of the wire electrode is changed by the capstan roller and the pinch roller, can be 0xc2x0 less than xcex8 less than 90xc2x0 being directed upward with respect to the traveling direction of the wire electrode, the direction of which is changed by the lower roller; and a wire guide for guiding the used wire electrode passing through between the capstan roller and the pinch roller to the wire cutter is arranged.
The present invention also provides a wire electric discharge machine in which a traveling direction of a wire electrode is changed by a lower roller arranged at a lower portion of a workpiece, the wire electrode is held and pulled by a capstan roller and pinch roller, and electric power for machining is supplied between the wire electrode and the workpiece while the wire electrode is traveling so that the workpiece is machined by electric discharge energy, the wire electric discharge machine comprising: a capstan roller and pinch roller arranged so that direction changing angle xcex8 of the wire electrode, by which the traveling direction of the wire electrode is changed by the capstan roller and the pinch roller, can be 0xc2x0 less than xcex8 less than 90xc2x0 being directed upward with respect to the traveling direction of the wire electrode, the direction of which is changed by the lower roller; a wire cutter for cutting the wire electrode after the wire electrode has passed through between the capstan roller and the pinch roller; a wire guide having a set of piping for supplying gas to support to convey the wire electrode when the gas is supplied in a direction by which the wire electrode is conveyed to the wire cutter, also having a set of piping for supplying gas to suppress a machining solution from flowing out from a gap between the capstan roller and the pinch roller when the gas is supplied toward the gap between the capstan roller and the pinch roller, the wire guide guiding the wire electrode, which has passed between the capstan roller and the pinch roller, to the wire cutter; and a compressed gas supply means for supplying compressed gas to the piping of the wire guide.
The present invention provides a wire electric discharge machine in which a traveling direction of a wire electrode is changed by a lower roller arranged at a lower portion of a workpiece, the wire electrode is held and pulled by a capstan roller and pinch roller, electric power for machining is supplied between the wire electrode and the workpiece while the wire electrode is traveling so that the workpiece is machined by electric discharge energy, and a wire recovery box for recovering the used wire electrode is provided, the wire electric discharge machine comprising: a capstan roller and pinch roller arranged so that direction changing angle xcex8 of the wire electrode, by which the traveling direction of the wire electrode is changed by the capstan roller and the pinch roller, can be 0xc2x0 less than xcex8 less than 90xc2x0 being directed upward with respect to the traveling direction of the wire electrode, the direction of which is changed by the lower roller; and a wire guide for guiding the used wire electrode passing through between the capstan roller and the pinch roller to the wire recovery box.
A wire electric discharge machine of the present invention comprises a set of piping for supplying gas to convey a wire to the wire guide.
In a wire electric discharge machine of the present invention, the angle xcex8 is set at about 30xc2x0.
Since the wire electric discharge machine of the present invention is composed as described above, the following effects can be provided. It is possible to suppress the breaking of a wire electrode. The wire electric discharge machine is suitable for automatizing the feed of a wire electrode. Further, when a wire cutter is used for the wire electric discharge machine, it is possible to prevent a machining solution from entering the wire cutter. When the wire cutter is not used for the wire electric discharge machine, it is possible to enhance the accommodation property of a used wire electrode.